High flow polyester composition, method of manufacture, and uses thereof

ABSTRACT

A high flow polyester composition is disclosed, which comprises at least one polyester, at least one flow enhancing ingredient of structure (III),  
                 
 
wherein R 3  is a C1-C20 alkyl group optionally having one or more hydroxy group substituents, a C3-C20 cycloalkyl group, a C6-C20 aryl group, a C1-C20 alkoxy group optionally having one or more hydroxy group substituents, or a C6-C20 aryloxy group; and an aromatic epoxy compound, in an amount sufficient to provide 5 to 300 milliequivalents of epoxy per kilogram of polyester. The composition further optionally comprises reinforcing fillers, impact modifiers, a property-enhancing thermoplastic such as polycarbonate and flame retardant chemicals. The compositions are suitable for making automotive, electric and electronic parts.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to and is a continuation-in-part ofU.S. application Ser. No. 11/216,792, filed Aug. 31, 2005, which isincorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION

The invention relates to a molding composition comprising polyester orits blends with other thermoplastics in the presence of a fluidityenhancer to decrease melt viscosity and improve processability.

Polyesters, copolyesters and their blends with other thermoplastics areemployed in making injection molded parts, films, blow-molded goods,pultruded sheets etc. These articles are used in automotive, electricaland electronic applications. The mechanical strength, electricalinsulation and easy processability are some of the key characteristicsof polyesters, which enable their use in these applications. The currentindustrial trend is about fabrication of parts with complicated and finedesigns with small flow cross-sectional areas, where fluidity ofconventional polyesters has been found inadequate.

To address the demanding requirements of high melt flowability, apolyester resin can be replaced by another polyester resin having lowerviscosity, but such low viscosity polyester adversely affects themechanical strength of the molded parts. The challenge therefore is toachieve high flowability of polyester molding compositions withoutaffecting their mechanical strength.

Among the various approaches known in reducing the melt viscosity ofpolymers such as polyamides and polyphenylene ethers, the use offlow-enhancing hydroxyl compounds is one of them. It has the potentialto provide the advantage of not having the need to modify the polymersand hence offers the scope of retaining most of the mechanicalproperties if used in effective small amounts. The following is adiscussion of prior art in this area.

A U.S. patent publication, U.S. Pat. No. 6,822,025 discloses the flowenhancement of a flame retardant composition based on polyphenyleneether/polystyrene resins by using polyhydric alcohols such aspentaerythritol, dipentaerythritol, pentitols, hexitols or saccharidesas a flow-enhancing additive. The '025 patent discloses that about 20%flow enhancement is achieved without loss of mechanical properties.However, as per '025 patent, the flow dependence is nearly independentof the amount of pentaerythritol used beyond 0.5% usage ofpentaerythritol.

A European patent publication, EP 1 041 109A2 describes the flowenhancement of glass filled polyamide compositions by using a polyhydricalcohol having melting point between 150 and 280 deg C., for example,pentaerythritol or dipentaerythritol. In polyamide compositions, bothpentaerythritol and dipentaerythritol showed identical flow enhancingeffects. In their study they also demonstrated that simple diol such as1,6-hexane diol is not effective as a flow promoting additive.

A European patent publication, EP 0 682 057A1 describes the flowenhancement of polyamide and polyester compositions with retention ofmechanical properties by using dendrimeric additives. Dendrimericcompounds in general are prepared in several separate steps from basicraw materials and are expensive.

A Japanese patent publication, JP 10310690 discloses the use ofpentaerythritol or 1,1,1-tris(hydroxymethyl)ethane and1,1,1-tri(hydroxymethyl)propane in a polybutylene terephthalate resinfor enhancing melt flow. The effect of these flow enhancing additives onother properties of the matrix resin and the effect of other ingredientsin the formulations were not disclosed.

Aside the above references on the flow enhancing properties ofpolyhydric alcohols such as pentaerythritol, a few other polyester flameretardant compositions have been known where pentaerythritol has beendisclosed as a char-forming additive. The char formation from polyhydricalcohol in the presence of acidic compounds is well documented inliterature.

The U.S. patent publication, U.S. Pat. No. 4,338,245 describes the useof pentaerythritol, dipentaerythritol or tripentaerythritol as achar-forming additive in polybutylene terephthalate resin containingmelammonium pentate as flame retardant. No flow or mechanical propertiesof these compositions were described in this '245 disclosure.

U.S. Pat. No. 5,424,344 discloses the use of pentaerythritol as a charformer in polyester composition containing hexavalent sulfur compound asa flame retardant, in addition to other components such as reinforcingfillers, fluoro polymer as a flow-enhancing additive etc. No mention ofheat-ageing stability of such compositions, nor flow enhancement due topentaerythritol were disclosed in this publication.

U.S. Pat. No. 6,025,419 discloses the use of pentaerythritol as a charformer in a polyester composition containing glass or mineralreinforcing fillers along with a melamine polyphosphate as a flameretardant material. No effect on flow or mechanical properties orheat-aging stability were disclosed in this patent publication.

U.S. Pat. No. 5,681,879 discloses the use of pentaerythritol ordipentaerythritol or 1,1,1-trimethylolpropane in a flame retardantpolyester composition containing halogenated flame retardants incombination with a synergist, antimony trioxide. Neither the flowenhancement due to these polyhydric alcohols nor the effect of otheringredients on the flow-promoting role of these additives was disclosedin this publication.

Flow promotion in the case of polyphenylene ether/polystyrene could be aresult of plasticizing action of polyhydric alcohol melts formed at hightemperatures prevailing in processing conditions. A hydroxy functionalmolecule may not react with polyphenylene ether derived from dialkylphenols or polystyrene derived from styrene monomers, as these polymersdo not have reactive functional groups that can react with a hydroxygroup. Similar scenario prevails in the case of polyamides, asalcoholysis of amide group is usually difficult (Smith and March, p.488, Advanced Organic Reactions-Reactions, Mechanisms, and Structure,John-Wiley, 5th edition, 2001) and requires highly reactive catalystssuch as titanium tetrachloride or triflic anhydride. The addedpolyhydric alcohols could remain as plasticizing domains in polyamidemedia thus giving rise to flow improvement of polyamides as suggested bythe melting point range preference for the added polyhydric alcohols inpolyamide compositions (reference: EP 1 041 109A2). On the contrary,flow promotion in polyesters by use of polyhydric alcohols poses specialchallenges owing to the propensity of polyesters to undergo reactionswith hydroxy with a likelihood of changes in mechanical properties ofpolyesters. From our study on the effect of ingredients on flowpromoting properties of some hydroxyl or amino functional molecules, wereport herein surprising improvements on the flow and thermal ageingresistance properties of polyester compounds without sacrificingmechanical properties due to inventive compositions disclosed herein.

BRIEF DESCRIPTION OF THE INVENTION

The present invention is aimed at providing a polyester composition,which is of high flowability, good mechanical properties, and goodheat-aging stability and/or hydrostability. One embodiment of thepresent invention is a polyester composition comprising of a polyesterand an alcohol ingredient of structural formula (I),

where, R1═NH₂ or CH₂OH; and R₂═CH₃, CH₃CH₂ or CH₂OH or any of C1-C20alkyl group which may have one or more hydroxy group substituent, C3-C20cycloalkyl group, C6-C20 aryl group, C1-C20 alkoxy group which may haveone or more hydroxy group substituent or C6-C20 aryloxy group.

In another embodiment, the composition additionally comprises of anacrylic impact modifier, a reinforcing filler or a flame retardantchemical.

In yet another embodiment, the composition additionally comprises athermoplastic resin other than an impact modifier.

In another aspect, the present disclosure relates to a compositioncomprising a polyester and an aminoalcohol of structural formula (III)

wherein R₃═CH₃, CH₂CH₃ or CH₂OH or any of C1-C20 alkyl group which mayhave one or more hydroxy group substituents, C3-C20 cycloalkyl group,C6-C20 aryl group, C1-C20 alkoxy group which may have one or morehydroxy group substituents or C6-C20 aryloxy group; and an aromaticepoxy compound, in an amount sufficient to provide 5 to 300milliequivalents of epoxy per kilogram of polyester.

Another aspect of the present disclosure relates to an articlecomprising the polyester, the aromatic epoxy compound, and the alcoholof formula (III).

Also described is a method of forming an article comprising thepolyester, the aromatic epoxy compound, and the amino alcohol of formula(III).

Various other features, aspects, and advantages of the present inventionwill become more apparent with reference to the following description,examples, and appended claims.

DETAILED DESCRIPTION OF THE INVENTION

The invention is based on the unexpected discovery that specifichydroxyl- or amino-functional molecules can improve the flow and thermalageing resistance properties of polyester compounds. Such improvementcan be obtained without sacrificing other advantageous mechanicalproperties. In addition, the inventors have unexpectedly found that useof a specific type of aminohydroxy-functional molecule in combinationwith a specific type of epoxide (an aromatic epoxide) can providefurther improvements in flow and thermal aging resistance. Unexpectedly,these improvements are not observed when the hydroxyl-functionalcompound is substituted for the aminohydroxy-functional compound.

The present invention may be understood more readily by reference to thefollowing detailed description of preferred embodiments of the inventionand the examples included herein. In this specification and in theclaims, which follow, reference will be made to a number of terms whichshall be defined to have the following meanings.

The singular forms “a”, “an” and “the” include plural referents unlessthe context clearly dictates otherwise.

“Optional” or “optionally” means that the subsequently described eventor circumstance may or may not occur, and that the description includesinstances where the event occurs and instances where it does not.

In one embodiment, the polyester composition comprises polyester resins.Methods for making polyester resins and the use of polyester resins inthermoplastic molding compositions are known in the art. Conventionalpolycondensation procedures are described in the following, see,generally, U.S. Pat. Nos. 2,465,319; 5,367,011 and 5,411,999, therespective disclosures of which are each incorporated herein byreference.

Typically polyester resins include crystalline polyester resins such aspolyester resins derived from an aryl, aliphatic or cycloaliphatic diol,or mixtures thereof, containing from 2 to about 10 carbon atoms or from2 to about 20 carbon atoms and at least one aromatic, aliphatic orcycloaliphatic dicarboxylic acid. Preferred polyesters are derived froman aliphatic diol and an aromatic dicarboxylic acid and have repeatingunits according to structural formula (II)

wherein, R′ is an alkyl radical compromising a dehydroxylated residuederived from an aliphatic or cycloaliphatic diol, or mixtures thereof,containing from 2 to about 20 carbon atoms. R is an aryl radicalcomprising a decarboxylated residue derived from an aromatic, aliphatic,or cycloaliphatic dicarboxylic acid, or a chemical equivalent thereof.In one embodiment of the present invention the polyester could be analiphatic polyester where at least one of R′ or R is a cycloalkylcontaining radical. The polyester is a condensation product where R′ isthe residue of an aryl, alkane or cycloaliphatic diol having 2 to 20carbon atoms or chemical equivalent thereof, and R is the decarboxylatedresidue derived from an aryl, aliphatic or cycloaliphatic diacid of 6 to20 carbon atoms or chemical equivalent thereof. Specific polyestersinclude poly(alkylene phthalate)s, poly(alkylene isophthalate)s,poly(alkylene terephthalate)s, poly(cycloalkylene terephthalate),poly(cycloalkylene cycloaliphatic dicarboxylate), poly(alkylenedicarboxylate), and the like. The polyester resins are typicallyobtained through the condensation or ester interchange polymerization ofthe diol or diol equivalent component with the diacid or diacid chemicalequivalent component.

The diacids meant to include carboxylic acids having two carboxyl groupseach useful in the preparation of the polyester resins of the presentinvention are preferably aliphatic, aromatic, cycloaliphatic. Examplesof diacids are cyclo or bicyclo aliphatic acids, for example, decahydronaphthalene dicarboxylic acids, norbornene dicarboxylic acids, bicyclooctane dicarboxylic acids, 1,4-cyclohexanedicarboxylic acid or chemicalequivalents, and most preferred is trans-1,4-cyclohexanedicarboxylicacid or a chemical equivalent. Linear dicarboxylic acids like adipicacid, azelaic acid, dicarboxyl dodecanoic acid, and succinic acid mayalso be useful. Chemical equivalents of these diacids include esters,alkyl esters, e.g., dialkyl esters, diaryl esters, anhydrides, salts,acid chlorides, acid bromides, and the like. Examples of aromaticdicarboxylic acids from which the decarboxylated residue R may bederived are acids that contain a single aromatic ring per molecule suchas, e.g., isophthalic or terephthalic acid,1,2-di(p-carboxyphenyl)ethane, 4,4′-dicarboxydiphenyl ether,4,4′-bisbenzoic acid and mixtures thereof, as well as acids containfused rings such as, e.g., 1,4- or 1,5-naphthalene dicarboxylic acids.In a preferred embodiment, the dicarboxylic acid precursor of residue Ris terephthalic acid or, alternatively, a mixture of terephthalic andisophthalic acids.

Some of the diols useful in the preparation of the polyester resins ofthe present invention are straight chain, branched, or cycloaliphaticalkane diols and may contain from 2 to 12 carbon atoms. Examples of suchdiols include but are not limited to ethylene glycol; propylene glycol,i.e., 1,2- and 1,3-propylene glycol; 2,2-dimethyl-1,3-propane diol;2-ethyl, 2- methyl, 1,3-propane diol; 1,4-butane diol, 1,4-but-2-enediol, 1,3- and 1,5-pentane diol; dipropylene glycol;2-methyl-1,5-pentane diol; 1,6-hexane diol; dimethanol decalin,dimethanol bicyclo octane; 1,4-cyclohexane dimethanol and particularlyits cis- and trans-isomers; triethylene glycol; 1,10-decane diol; andmixtures of any of the foregoing. Chemical equivalents to the diolsinclude esters, such as dialkylesters, diaryl esters, and the like.Typically the polyester resin may comprise one or more resins selectedfrom linear polyester resins, branched polyester resins and copolymericpolyester resins. In one embodiment, the diol precursor of residue R′ isa C₂-C₄ alkanediol or a chemical equivalent thereof. In yet anotherembodiment, the diol precursor of residue R′ is a C₂-C₄ alkanediol or achemical equivalent thereof, and the dicarboxylic acid precursor ofresidue R is derived from a mixture of terephthalic acid and isophthalicacid or a chemical equivalent thereof.

In one embodiment, the above polyesters with about 1 to about 70% byweight, of units derived from polymeric aliphatic acids and/or polymericaliphatic polyols to form copolyesters. The aliphatic polyols includeglycols, such as poly(ethylene glycol) or poly(butylene glycol). Inanother embodiment suitable copolymeric polyester resins include, e.g.,polyesteramide copolymers, cyclohexanedimethanol-terephthalicacid-isophthalic acid copolymers and cyclohexanedimethanol-terephthalicacid-ethylene glycol (“PCTG” or “PETG”) copolymers. When the molarproportion of cyclohexanedimethanol is higher than that of ethyleneglycol the polyester is termed PCTG. When the molar proportion ofethylene glycol is higher than that of cyclohexane dimethanol thepolyester is termed PETG.

The most preferred polyesters are poly(ethylene terephthalate) (“PET”),and poly(1,4-butylene terephthalate), (“PBT”), poly(ethylenenaphthalate) (“PEN”), poly(butylene naphthalate), (“PBN”),poly(propylene terephthalate) (“PPT”), poly(cyclohexane dimethanolterephthalate), (PCT), poly(cyclohexane-1,4-dimethylenecyclohexane-1,4-dicarboxylate) also referred to aspoly(1,4-cyclohexane-dimethanol 1,4-dicarboxylate) (PCCD) and thecopolyesters PCTG and PETG.

The preferred polyesters are preferably polyester polymers have anintrinsic viscosity (as measured in phenol/tetrachloro ethane (60:40,volume/volume ratio) at 25° C.) ranging from at least about 0.4 to about2.0 deciliters per gram. Polyesters branched or unbranched and generallywill have a weight average molecular weight of from about 5,000 to about130,000 g/mol, specifically 10,000 to about 120,000 g/mol againstpolystyrene standard, as measured by gel permeation chromatography inchloroform/ hexafluoroisopropanol (5:95, volume/volume ratio) at 25° C.It is contemplated that the polyesters have various known end groups.

A mixture of polyester resins with differing viscosities may be used tomake a blend to allow for control of viscosity of the final formulation.Blends of polyesters may also be employed in the composition. Preferredpolyester blends are made from poly(ethylene terephthalate) andpoly(1,4-butylene terephthalate).

The polyester component may be prepared by procedures well known tothose skilled in this art, such as by condensation reactions. Thecondensation reaction may be facilitated by the use of a catalyst, withthe choice of catalyst being determined by the nature of the reactants.The various catalysts for use herein are very well known in the art andare too numerous to mention individually herein. Generally, however,when an alkyl ester of the dicarboxylic acid compound is employed, anester interchange type of catalyst is preferred, such as Ti(OC₄H₉)₆ inn-butanol.

Depending on the nature of applications, the amount of polyester used ina composition varies. For example, in automotive applications andtransparent film applications, blends of polycarbonate and polyester arepreferred, where, the polyester amount being <40%. Normally, inelectrical and electronic applications, the compositions comprisepredominantly polyester in an amount of >60%.

The polyhydric alcohol additive used in the polyester compositions ofthis invention correspond to the structure, I,

where, R₁═NH₂ or CH2OH; and R₂═CH₃, CH₃CH₂ or CH₂OH or any of C1-C20alkyl group which may have one or more hydroxy group substituent, C3-C20cycloalkyl group, C6-C20 aryl group, C1-C20 alkoxy group which may haveone or more hydroxy group substituent or C6-C20 aryloxy group. Astructure with at least three hydroxymethyl groups or at least twohydroxymethyl groups and one amino group is preferred.

Examples of compounds represented by the formula I include1,1-dimethylol-1-aminoethane (DAE), 1,1-dimethylol-1-aminopropane (DAP),tris(hydroxymethyl)aminomethane (THAM), 1,1,-trimethylolpropane (TMP),1,1,1-trimethylolethane, pentaerythritol (PETOL), dipentaerythritol,tripentaerythritol and 1,1,1-trimethylol pentane. Of these compounds,THAM, DAP, TMP and PETOL are more preferred. There are contradictoryconclusions on the reactivity of amino group-containing alcohol, THAMrelative to PETOL. Their relative reactivities with small molecule esterbonds depend on conditions employed. (Reference: T. C. Bruice and J. L.York., J. Am Chem. Soc., 1961, 83, p. 1382).

It has further unexpectedly been discovered that use of the aminoalcoholin combination with an aromatic epoxy compound results in improvementsin melt flow without sacrificing resistance to hydrolytic environmentsand to heat aging, and establishes a balance of improved flow propertiesand physical resistance. This improvement is not observed with otherepoxy compounds or with the compound containing solely hydroxyl groups.

Exemplary aminoalcohol additives correspond to the structure (III),

wherein R₃ is as defined above, that is, R₃ is a C1-C20 alkyl groupoptionally substituted with one or more hydroxy group substituents, aC3-C20 cycloalkyl group, a C6-C20 aryl group, a C1-C20 alkoxy groupoptionally substituted with one or more hydroxy group substituents, or aC6-C20 aryloxy group. In one embodiment, R₃ is CH₃, CH₂CH₃, or CH₂OH.Mixtures of different polyhydric alcohols can be used.

Examples of compounds represented by the formula (III) include1,1-dimethylol-1-aminoethane (DAE), 1,1-dimethylol-1-aminopropane (DAP),and tris(hydroxymethyl)aminomethane (THAM). Of the preceding alcohols,THAM and DAP are advantageous.

In this embodiment, the aminoalcohol is amount of 0.05 to 2% by weight,specifically 0.1 to 1% by weight of the polyester in the composition.

“Aromatic epoxy compounds” as used herein refer to compounds comprisingat least one aromatic moiety and at least one epoxy functionality. Otherfunctional groups, e.g., carboxylic acids, carboxylic acid esters,halogens, nitrile, nitro, sulfhydryl, alkoxy, aryloxy, and the like canalso be present. In one embodiment, the aromatic epoxy compound willcontain only carbon, hydrogen and oxygen, and will have an epoxyequivalent weight of 10 to 5,000, more specifically 50 to 4,000, evenmore specifically 100 to 3,000.

Exemplary aromatic epoxy compounds correspond to the structure (IV)

wherein R^(a′) and R^(b′) are each independently halogen or C₁₋₁₂ alkyl,X^(a) is a substituted or unsubstituted C₁₋₁₈ alkylidene bridging groupor a substituted or unsubstituted C₃₋₁₈ cycloalkylidene bridging group,n is 1 to 6, and r and s are each independently 0 to 4. Exemplaryaromatic alcohols of this type include bisphenol epoxy resins,specifically bisphenol-A epoxy resins, bisphenol-F epoxy resins, and thelike. The aromatic epoxy compounds are commercially available.

Effective amounts of the aromatic epoxy compound are readily determinedby one of ordinary skill in the art without undue experimentation, basedon the amount and type of polyester, the amount and type of epoxide, andthe amount and type of catalyst, using the guidance provided herein.Typically, small amounts are used, for example amounts effective toprovide 5 to 300 milliequivalents of epoxy per kg of polyester, morespecifically, 15 to 100 milliequivalents of epoxy per kilogram ofpolyester.

Another optional component in this embodiment of the composition is acatalyst. Catalysts can be selected from hydroxides, hydrides, amides,carbonates, borates, phosphates, C₂-C₁₈ enolates, C₂-C₃₆ dicarboxylates,C₂-C₃₆ metal carboxylates, Lewis acids, C₁-C₃₆ tetraalkyl ammoniumhydroxides or acetates, C₁-C₃₆ tetraalkyl phosphonium hydroxides oracetates, alkali or alkaline earth metal salts of a negatively chargedpolymer, or the like, or a combination comprising at least one of theforegoing catalysts. Specific catalysts include sodium stearate, sodiumcarbonate, sodium acetate, sodium bicarbonate, sodium benzoate, sodiumcaproate, potassium oleate, boron compounds, or a mixture comprising atleast one of the foregoing catalysts.

Effective amounts of the catalyst are readily determined by one ofordinary skill in the art without undue experimentation, based on theamount and type of polyester, the amount and type of epoxide, and theamount and type of catalyst, using the guidance provided herein. In oneembodiment, the catalyst is present in an amount of about 0.001 to about1 weight percent, specifically in an amount of about 0.003 to about 0.1weight percent, based on the total weight of the composition.

Polyester compositions comprising the aminoalcohol of formula (III), thearomatic epoxy compound, and an optional catalyst have improved flowproperties at high temperatures compared to the same compositionswithout the aminoalcohol, the aromatic epoxy compound, and an optionalcatalyst. Spiral flow, which can be measured in an injection moldingmachine with a spiral mold at a melt temperature of 250° C. to 260° C.,a mold temperature of 66° C., a gauge of 1.5 millimeters, and a boostpressure of 10 megapascals, exhibits an improvement of 20 percent ormore, specifically an improvement of 25 percent or more, even morespecifically an improvement of 30 percent or more, compared to thespiral flow of the same composition without the aminoalcohol, thearomatic epoxy compound, and an optional catalyst.

Similarly, the capillary viscosity of polyester compositions comprisingthe aminoalcohol of formula (III), the aromatic epoxy compound, and anoptional catalyst shows an improvement over polyester compositionswithout these additives. Capillary viscosity can be measured inaccordance with ASTM D3835 or ISO D11433, wherein dried pellets areextruded through a capillary rheometer and the force at varied shearrates is determined. This allows an estimation of shear viscosity.Capillary viscosities of polyester compositions comprising theaminoalcohol, the aromatic epoxy compound, and an optional catalyst showan improvement of 20 percent or more, specifically an improvement of 25percent or more, even more specifically an improvement of 30 percent ormore, compared to the capillary viscosities of the same compositionwithout the aminoalcohol, the aromatic epoxy compound, and an optionalcatalyst.

Polyester compositions comprising the aminoalcohol, the aromatic epoxycompound, and an optional catalyst can further have improved retentionof impact properties after heat aging, compared to polyestercompositions without both the aminoalcohol and the aromatic epoxycompound. An article molded from these compositions retains at least60%, more specifically at least 75%, even more specifically at least 85%of its tensile strength, measured in accordance with ASTM D638, afteraging at 90° C. for 168 hours at 95% relative humidity.

In a particularly advantageous embodiment, an improvement in impactproperties is observed under conditions of heat, humidity, and pressuresimilar to those encountered during autoclaving. Accordingly, an articlecomprising a polyester, the aminoalcohol, the aromatic epoxy compound,and an optional catalyst retains more of a tensile property after agingunder conditions of high heat, humidity, and pressure than the samecomposition without the diepoxide. In particular, an article molded fromthese compositions more of its tensile stress, after aging at 110° C.,at 140 kilopascals, for 120 hours at 100% relative humidity, measured inaccordance with ASTM D638.

In a specific embodiment, the foregoing polyester compositions can haveboth improved flow and improved tensile properties compared to acomposition without both of the polyhydric alcohol and the diepoxycompound.

The composition can further comprise an impact modifier. Impactmodifiers, as used herein, include materials effective to improve theimpact properties of polyesters.

Useful impact modifiers are substantially amorphous copolymer resins,including but not limited to acrylic rubbers, ASA rubbers, dienerubbers, organosiloxane rubbers, EPDM rubbers, SBS or SEBS rubbers, ABSrubbers, MBS rubbers and glycidyl ester impact modifiers.

The acrylic rubber is a preferably core-shell polymer built up from arubber-like core on which one or more shells have been grafted. Typicalcore material consists substantially of an acrylate rubber. Preferablethe core is an acrylate rubber of derived from a C4 to C12 acrylate.Typically, one or more shells are grafted on the core. Usually theseshells are built up for the greater part from a vinyl aromatic compoundand/or a vinyl cyanide and/or an alkyl(meth)acrylate and/or(meth)acrylic acid. Preferable the shell is derived from analkyl(meth)acrylate, more preferable a methyl(meth)acrylate. The coreand/or the shell(s) often comprise multi-functional compounds that mayact as a cross-linking agent and/or as a grafting agent. These polymersare usually prepared in several stages. The preparation of core-shellpolymers and their use as impact modifiers are described in U.S. Pat.Nos. 3,864,428 and 4,264,487. Especially preferred grafted polymers arethe core-shell polymers available from Rohm & Haas under the trade namePARALOID®, including, for example, PARALOID® EXL3691 andPARALOID®EXL3330, EXL3300 and EXL2300. Core shell acrylic rubbers can beof various particle sizes. The preferred range is from 300-800 nm,however larger particles, or mixtures of small and large particles, mayalso be used. In some instances, especially where good appearance isrequired acrylic rubber with a particle size of 350-450 nm may bepreferred. In other applications where higher impact is desired acrylicrubber particle sizes of 450-550 nm or 650-750 nm may be employed.

Acrylic impact modifiers contribute to heat stability and UV resistanceas well as impact strength of polymer compositions. Other preferredrubbers useful herein as impact modifiers include graft and/or coreshell structures having a rubbery component with a Tg (glass transitiontemperature) below 0° C., preferably between about −40° to about −80°C., which comprise poly-alkylacrylates or polyolefins grafted withpoly(methyl)methacrylate or styrene-acrylonitrile copolymer. Preferablythe rubber content is at least about 10% by weight, most preferably, atleast about 50%.

In another aspect of the invention the acrylic core shell rubbercomprises a multi-phase composite interpolymer comprising about 25 to 95weight percent of a first acrylic elastomeric phase polymerized from amonomer system comprising about 75 to 99.8% by weight C₁ to C₁₄ alkylacrylate, 0.1 to 5% by weight crosslinking member, 0.1 to 5% by weightgraftlinking monomer, said crosslinking monomer being apolyethylenically unsaturated monomer having a plurality of additionpolymerizable reactive groups and about 75 to 5 weight percent of afinal, rigid thermoplastic acrylic or methacrylic phase polymerized inthe presence of said elastomer.

Typical other rubbers for use as impact modifiers herein are thebutadiene core-shell polymers of the type available from Rohm & Haasunder the trade name PARALOID® EXL2600. Most preferably, the impactmodifier will comprise a two stage polymer having a butadiene basedrubbery core, and a second stage polymerized from methylmethacrylatealone or in combination with styrene. Impact modifiers of the type alsoinclude those that comprise acrylonitrile and styrene grafted ontocross- linked butadiene polymer, which are disclosed in U.S. Pat. No.4,292,233 herein incorporated by reference.

Other suitable impact modifiers may be mixtures comprising core shellimpact modifiers made via emulsion polymerization using alkyl acrylate,styrene and butadiene. These include, for example, methylmethacrylate-butadiene-styrene (MBS) and methylmethacrylate-butylacrylate core shellrubbers.

Among the other suitable impact modifiers are the so-called blockcopolymers and rubbery impact modifiers, for example, A—B—A triblockcopolymers and A—B diblock copolymers. The A—B and A—B—A type blockcopolymer rubber additives which may be used as impact modifiers includethermoplastic rubbers comprised of one or two alkenyl aromatic blockswhich are typically styrene blocks and a rubber block, e.g., a butadieneblock which may be partially hydrogenated. Mixtures of these triblockcopolymers and diblock copolymers are especially useful.

Suitable A—B and A—B—A type block copolymers are disclosed in, forexample, U.S. Pat. Nos. 3,078,254; 3,402,159; 3,297,793; 3,265,765; and3, 594,452 and U.K. Pat. No. 1,264,741. Examples of typical species ofA—B and A—B—A block copolymers include polystyrene-polybutadiene (SB),polystyrene-poly(ethylene-propylene), polystyrene-polyisoprene,poly(a-methylstyrene)-polybutadiene,polystyrene-polybutadiene-polystyrene (SBS),polystyrene-poly(ethylene-propylene)-polystyrene,polystyrene-polyisoprene-polystyrene andpoly(α-methylstyrene)-polybutadiene-poly(α-methylstyrene), as well asthe selectively hydrogenated versions thereof, and the like. Mixturescomprising at least one of the aforementioned block copolymers are alsouseful. Such A—B and A—B—A block copolymers are available commerciallyfrom a number of sources, including Phillips Petroleum under thetrademark SOLPRENE, Shell Chemical Co., under the trademark KRATON,Dexco under the trade name VECTOR, and Kuraray under the trademarkSEPTON.

The composition can also comprise a vinyl aromatic-vinyl cyanidecopolymer. Suitable vinyl cyanide compounds include acrylonitrile andsubstituted vinyl cyanides such a methacrylonitrile. Preferably theimpact modifier comprises styrene-acrylonitrile copolymer (hereinafterSAN). The preferred SAN composition comprises at least 10, preferably 25to 28, percent by weight acrylonitrile (AN) with the remainder styrene,para-methyl styrene, or alpha methyl styrene. Another example of SANsuseful herein include those modified by grafting SAN to a rubberysubstrate such as, for example, 1,4-polybutadiene, to produce a rubbergraft polymeric impact modifier. High rubber content (greater than 50%by weight) resin of this type (HRG-ABS) may be especially useful forimpact modification of polyester resins and their polycarbonate blends.

Another class of preferred impact modifiers, referred to as high rubbergraft ABS modifiers, comprise greater than or equal to about 90% byweight SAN grafted onto polybutadiene, the remainder being free SAN. ABScan have butadiene contents between 12% and 85% by weight and styrene toacrylonitrile ratios between 90:10 and 60:40. Preferred compositionsinclude: about 8% acrylonitrile, 43% butadiene and 49% styrene, andabout 7% acrylonitrile, 50% butadiene and 43% styrene, by weight. Thesematerials are commercially available under the trade names BLENDEX 336and BLENDEX 415 respectively (Crompton Co.).

Improved impact strength is obtained by melt compounding polybutyleneterephthalate with ethylene homo- and copolymers functionalized witheither acid or ester moieties as taught in U.S. Pat. Nos. 3,405,198;3,769,260; 4,327,764; and 4,364,280. Polyblends of polybutyleneterephthalate with a styrene-alpha-olefin-styrene triblock are taught inU.S. Pat. No. 4,119,607. U.S. Pat. No. 4,172,859 teaches impactmodification of polybutylene terephthalate with random ethylene-acrylatecopolymers and EPDM rubbers grafted with a monomeric ester or acidfunctionality.

Preferred impact modifiers include core-shell impact modifiers, such asthose having a core of poly(butyl acrylate) and a shell of poly(methylmethacrylate).

Impact modifiers may be present in 0.1 to about 30 weight percent. Auseful amount of impact modifier is about 1 to about 30 weight percent,preferably about 5 to about 15 weight percent, more preferably about 6to about 12 weight percent, wherein the weight percentages are based onthe entire weight of the composition.

Normally, inclusion of impact modifiers, which are particulate innature, increases the melt viscosity of polyester compositions.Enhancing the melt flow of impact modified polyester compositionscomprising any of the aforesaid impact modifiers is a need in theindustry.

Additionally, it may be desired to employ inorganic fillers in thethermoplastic resin provide higher tensile modulus, density and lowcoefficient of thermal expansion without deleteriously affecting theother favorable properties.

Incorporation of inorganic fillers often leads to increase of viscosityof polymer compositions. Enhancement of flow of such compositions ishighly desirable.

Typical inorganic fillers include: alumina, amorphous silica, anhydrousalumino silicates, mica, wollastonite, barium sulfate, zinc sulfide,clays, talc, metal oxides such as titanium dioxide. Low levels (0.1-10.0wt. %) of very small particle size (largest particles less than 10microns in diameter) are preferred.

The polyester resins of the invention may be further blended withreinforcements, fillers and colorants.

Reinforcing fiber and fillers may comprise from about 5 to about 50weight percent of the composition, preferably from about 10 to about 35weight percent based on the total weight of the composition. Thepreferred reinforcing fibers are glass, ceramic and carbon and aregenerally well known in the art, as are their methods of manufacture. Inone embodiment, glass is preferred, especially glass that is relativelysoda free. Fibrous glass filaments comprised oflime-alumino-borosilicate glass, which is also known as “E” glass areoften especially preferred. Glass fiber is added to the composition togreatly increase the flexural modulus and strength, albeit making theproduct more brittle. The glass filaments can be made by standardprocesses, e.g., by steam or air blowing, flame blowing and mechanicalpulling. The preferred filaments for plastic reinforcement are made bymechanical pulling. For achieving optimal mechanical properties fiberdiameter between 6-20 microns are required with a diameter of from 10-15 microns being preferred. In preparing the molding compositions it isconvenient to use the fiber in the form of chopped strands of from about⅛″ (3 mm) to about ½″ (13 mm) long although roving may also be used. Inarticles molded from the compositions, the fiber length is typicallyshorter presumably due to fiber fragmentation during compounding of thecomposition. The length of such short glass fibers present in finalmolded compositions is less than about 4 mm. The fibers may be treatedwith a variety of coupling agents to improve adhesion to the resinmatrix. Preferred coupling agents include; amino, epoxy, amide ormercapto functionalized silanes. Organometallic coupling agents, forexample, titanium or zirconium based organometallic compounds, may alsobe used.

Other preferred sizing-coated glass fibers are commercially availablefrom Owens Corning Fiberglass as, for example, OCF K filament glassfiber 183F.

In another embodiment, long glass fibers can be used, wherein acontinuous glass fiber bundle containing thousands of glass fibermonofilaments having a diameter in the range, 10-24 μm, preferably 13-18μm is impregnated with a melted thermoplastic preferably a polyester.After cooling, the impregnated bundle is cut into pellets having alength of >5 mm, preferably, above >9 mm, as prepared by the applicationof a process known as the pullout or pultrusion process. Forimpregnation, a high flow polyester of the present invention can be usedin order to improve the wetting rate of the filaments to make long glassfiber pellets. These pellets can be incorporated into the polyestercompositions of the invention, to get long fiber glass reinforcedpolyester compositions. The length of long glass fiber present in moldedcomposition prepared by this method is typically greater than thatprepared by incorporation of short fibers and predominant portion of thelong glass fibers present have a length >4 mm in the molded part. Suchlong fiber glass reinforced compositions can be used for differentmolding techniques such as injection molding, compression molding,thermoforming and the like. As in the case of short fibers, the longfibers may also be treated with a variety of coupling agents to improveadhesion to resin. For those skilled in the art, a continuous processsuch as pushtrusion technique for direct incorporation of long glassfibers in high flow polyester compositions will also be possible.

Other fillers and reinforcing agents may be used alone or in combinationwith reinforcing fibers. These include but are not limited to: carbonfibrils, mica, talc, barites, calcium carbonate, wollastonite, milledglass, flaked glass, ground quartz, silica, zeolites, and solid orhollow glass beads or spheres, clay, fibrillated tetrafluoroethylene,polyester fibers or aramid fibers.

The glass fibers may be blended first with the aromatic polyester andthen fed to an extruder and the extrudate cut into pellets, or, in apreferred embodiment, they may be separately fed to the feed hopper ofan extruder. In a highly preferred embodiment, the glass fibers may befed downstream in the extruder to minimize attrition of the glass.Generally, for preparing pellets of the composition set forth herein,the extruder is maintained at a temperature of approximately 480° F. to550° F. The pellets so prepared when cutting the extrudate may beone-fourth inch long or less. As stated previously, such pellets containfinely divided uniformly dispersed glass fibers in the composition. Thedispersed glass fibers are reduced in length as a result of the shearingaction on the chopped glass strands in the extruder barrel.

The composition of the present invention may include additionalcomponents that do not interfere with the previously mentioned desirableproperties but enhance other favorable properties such as bis epoxychain extenders, chain extension catalysts, monoepoxy chain terminators,heat stabilizers, antioxidants, colorants, including dyes and pigments,lubricants, mold release materials, nucleating agents or ultra violet(UV) stabilizers. Examples of lubricants are alkyl esters, for examplepentaerythritol tetrastearate (PETS), alkyl amides, such as ethylenebis-stearamide, and polyolefins, such as polyethylene.

In a specific embodiment, the composition includes a flame retardingcomponent. The flame retarding component can be added to the compositionto suppress, reduce, delay or modify the propagation of a flame througha composition or an article based on the composition. Specific exemplaryflame retarding components include halogenated hydrocarbons (chlorine-and bromine-containing compounds and reactive flame retardants),inorganic flame retardants (boron compounds, antimony oxides, aluminumhydroxide, molybdenum compounds, zinc and magnesium oxides), phosphorouscontaining compounds (organic phosphates, phosphinates, phosphites,phosphonates, phosphines, halogenated phosphorus compounds and inorganicphosphorus-containing salts) and nitrogen containing compounds such asmelamine cyanurate. Combinations comprising one or more of the foregoingtypes of flame retardant components can be used.

Specific inorganic flame retardants include metal hydroxides, antimonycompounds, boron compounds, other metal compounds, phosphorouscompounds, and other inorganic flame retarding compounds. Examples ofsuitable metal hydroxides include magnesium hydroxide, aluminumhydroxide, and other metal hydroxides. Examples of suitableantimony-based flame retardants include antimony trioxide, sodiumantimonate, antimony pentoxide, and other antimony-based inorganiccompounds. Examples of suitable boron compounds include zinc borate,boric acid, borax, as well as other boron-based inorganic compounds.Examples of other metal compounds include molybdenum compounds,molybdenum trioxide, ammonium octamolybdate (AOM), zirconium compounds,titanium compounds, zinc compounds such as zinc stannate, zinchydroxy-stannate, as well as others, and combinations comprising atleast one of the foregoing inorganic flame retardants.

Specific examples of suitable halogenated organic flame retardantstetrabromobisphenol A, octabromobiphenyl ether, decabromodiphenyl ether,bis(tribromophenoxy) ethane, tetrabromobiphenyl ether,hexabromocyclododecane, tribromophenol, bis(tribromophenoxy) ethane,tetrabromobisphenol A polycarbonate oligomers, and tetrabromobisphenol Aepoxy oligomers. Typically halogenated aromatic flame retardants includetetrabromobisphenol A polycarbonate oligomer, which, if desired, areendcapped with phenoxy radicals, or with brominated phenoxy radicals,polybromophenyl ether, brominated polystyrene, brominated BPApolyepoxide, brominated imides, brominated polycarbonate, poly(haloarylacrylate), poly(haloaryl methacrylate), e.g.,poly(pentabromobenzyl)acrylate, or a combination comprising at least oneof the foregoing. Also included within the class of halogenated flameretardants are brominated polystyrenes such as poly-dibromostyrene andpolytribromostyrene, decabromobiphenyl ethane, tetrabromobiphenyl,brominated alpha,omega-alkylene-bis-phthalimides, e.g.,N,N′-ethylene-bis-tetrabromophthalimide, oligomeric brominatedcarbonates, especially carbonates derived from tetrabromobisphenol A,and brominated epoxy resins.

Chlorinated flame retardants include chlorinated paraffins, and bis(hexachlorocyclopentadieno)cyclooctane, as well other such functionallyequivalent materials.

Examples of suitable phosphorous-containing flame retardants include redphosphorus and ammonium polyphosphate, as well as organophoshorus flameretardants, e.g., halogenated phosphates and other non-halogenatedcompounds. Examples of such materials includetris(1-chloro-2-propyl)phosphate, tris(2-chloroethyl)phosphate,tris(2,3-dibromopropyl)phosphate, phosphate esters, trialkyl phosphates,triaryl phosphates, aryl-alkyl phosphates, and combinations thereof.Other flame retardants can include polyols, phosphonium derivatives,phosphonates, phosphanes, and phosphines.

Specific phosphorous-containing compounds include phosphates of theformula:

wherein each R is independently a C₁₋₁₈ alkyl, cycloalkyl, aryl, orarylalkyl, e.g., cyclohexyl, isopropyl, isobutyl, and the like;phosponates of the formula:

wherein X is H, and each R is independently a C₁₋₁₈ alkyl, cycloalkyl,aryl, or arylalkyl, e.g., cyclohexyl, isopropyl, isobutyl, and the like;phosphinates of the formula

wherein X and Y is H, and R is a C₁₋₁₈ alkyl, cycloalkyl, aryl, orarylalkyl, e.g., cyclohexyl, isopropyl, isobutyl, and the like;phosphine oxides of the formula:

wherein X, Y, and Z are H and R, is a C₁₋₁₈ alkyl, cycloalkyl, aryl,arylalkyl, e.g., cyclohexyl, isopropyl, isobutyl, and the like;phosphines of the formula:

wherein X, Y, and Z is each independently a H, C₁₋₁₈ alkyl, cycloalkyl,aryl, arylalkyl, and the like; or a phosphite of the formula:

wherein each R is independently the same or different can be selectedfrom the group of C₁₋₁₈ alkyl, cycloalkyl, aryl, or arylalkyl, e.g.,cyclohexyl, isopropyl, isobutyl, and the like, and H.

As such, suitable flame retarding agents that may be added may beorganic compounds that include phosphorus, bromine, and/or chlorine.Non-brominated and non-chlorinated phosphorus-containing flameretardants may be preferred in certain applications for regulatoryreasons, for example organic phosphates and organic compounds containingphosphorus-nitrogen bonds.

One type of exemplary organic phosphate is an aromatic phosphate of theformula (GO)₃P═O, wherein each G is independently an alkyl, cycloalkyl,aryl, alkylaryl, or aralkyl group, provided that at least one G is anaromatic group. Two of the G groups may be joined together to provide acyclic group, for example, diphenyl pentaerythritol diphosphate, whichis described by Axelrod in U.S. Pat. No. 4,154,775. Other suitablearomatic phosphates may be, for example, phenyl bis(dodecyl)phosphate,phenyl bis(neopentyl)phosphate, phenylbis(3,5,5′-trimethylhexyl)phosphate, ethyl diphenyl phosphate,2-ethylhexyl di(p-tolyl)phosphate, bis(2-ethylhexyl) p-tolyl phosphate,tritolyl phosphate, bis(2-ethylhexyl)phenyl phosphate, tri(nonylphenyl)phosphate, bis(dodecyl) p-tolyl phosphate, dibutyl phenyl phosphate,2-chloroethyl diphenyl phosphate, p-tolylbis(2,5,5′-trimethylhexyl)phosphate, 2-ethylhexyl diphenyl phosphate, orthe like. A specific aromatic phosphate is one in which each G isaromatic, for example, triphenyl phosphate, tricresyl phosphate,isopropylated triphenyl phosphate, and the like. Di- or polyfunctionalaromatic phosphorus-containing compounds are also useful, for example,compounds of the formulas below:

wherein each G¹ is independently a hydrocarbon having 1 to about 30carbon atoms; each G² is independently a hydrocarbon or hydrocarbonoxyhaving 1 to about 30 carbon atoms; each X_(m) is independently a bromineor chlorine; m is 0 to 4; and n is 1 to about 30. Examples of suitabledi- or polyfunctional aromatic phosphorus-containing compounds includeresorcinol tetraphenyl diphosphate (RDP), the bis(diphenyl) phosphate ofhydroquinone and the bis(diphenyl) phosphate of bisphenol-A,respectively, their oligomeric and polymeric counterparts, and the like.

Other exemplary suitable flame retarding compounds containingphosphorus-nitrogen bonds, include phosphonitrilic chloride, phosphorusester amides, phosphoric acid amides, phosphonic acid amides, phosphinicacid amides, and tris(aziridinyl)phosphine oxide. When present,phosphorus-containing flame retardants are generally present in amountsof about 1 to about 20 parts by weight, based on 100 parts by weight ofthe total resin in the final composition.

In one embodiment, the flame retarding polyester composition includes aflame retarding quantity of one or a mixture of nitrogen-containingflame retardants such as triazines, guanidines, cyanurates, andisocyanurates. Suitable triazines have the formula

wherein R¹, R², and R³ are independently C₁₋₁₂ alkyl, C₁₋₁₂ alkoxyl,C₆₋₁₂ aryl, amino, C₁₋₁₂ alkyl-substituted amino, or hydrogen. Highlysuitable triazines include 2,4,6-triamine-1,3,5-triazine (melamine, CASReg. No. 108-78-1), melamine derivatives, melam, melem, melon, ammeline(CAS Reg. No. 645-92- 1), ammelide (CAS Reg. No. 645-93-2),2-ureidomelamine, acetoguanamine (CAS Reg. No. 542-02-9), benzoguanamine(CAS Reg. No. 91-76-9), and the like. Salts/adducts of these compoundswith boric acid or phosphoric acid may be used in the composition.Examples include melamine pyrophosphate and melamine polyphosphate.Suitable cyanurate/isocyanurate compounds include salts/adducts of thetriazine compounds with cyanuric acid, such as melamine cyanurate andany mixtures of melamine salts.

Suitable guanidine compounds include guanidine; aminoguanidine; and thelike; and their salts and adducts with boric acid, carbonic acid,phosphoric acid, nitric acid, sulfuric acid, and the like; and mixturescomprising at least one of the foregoing guanidine compounds.

The nitrogen-containing flame retardants are often used in combinationwith one or more phosphorous-based compounds, for example thephosphinates and diphosphinates set forth in U.S. Pat. No. 6,255,371 toSchosser et al. Specific phosphinates include aluminumdiethylphosphinate (DEPAL), and zinc diethylphosphinate (DEPZN). Thephosphinates have the formula (1)

and/or formula (2),

and or polymers comprising units derived from formulas (1) or (2),wherein R₁ and R₂ are the same or different, and are H, C₁₋₆ alkyl(linear or branched), and/or aryl; R₃ is C₁₋₁₀ alkylene, (linear orbranched), C₆₋₁₀ arylene, C₆₋₁₀ alkylarylene or C₆₋₁₀ arylalkylene; M isany metal, e.g., magnesium, calcium, aluminum or zinc, m is 1, 2 or 3; nis 1, 2 or 3; and x is 1 or 2. In one embodiment, R₁ and R₂ can be H.This results in a hypophosphite, a subset of phosphinate, such ascalcium hypophosphite, aluminum hypophosphite, and the like.

The flame retardants are typically used with a synergist, particularlyinorganic antimony compounds. Such compounds are widely available or canbe made in known ways. Typical inorganic synergist compounds includeSb₂O₅, SbS₃, sodium antimonate and the like. Especially suitable isantimony trioxide (Sb₂O₃). Synergists such as antimony oxides aretypically used in an amount of about 0.5 to 15 by weight, based on theweight of resin in the final composition.

Also, the present composition may contain polytetrafluoroethylene (PTFE)type resins or copolymers, which are used either to reduce dripping inflame retardant thermoplastics or to form fibrillar network in thecomposition. In one embodiment the fluoropolymer is at least partiallyencapsulated by an encapsulating thermoplastic polymer, for examplePTFE/SAN, synthesized by aqueous emulsion polymerization as disclosed inU.S. Pat. No. 5,804,654.

Flame retardant additives are desirably present in an amount at leastsufficient to reduce the flammability of the polyester resin, preferablyto a UL94 V-0 rating. The amount will vary with the nature of the resinand with the efficiency of the additive. The amount of the flameretarding component is generally at least 1 wt. %, based on the weightof resin in the final composition. In one embodiment, the amount of theflame retarding component is from 5 wt. % to 30 wt%, based on the weightof resin in the final composition. In another embodiment, the amount ofthe flame retarding component is from 10 to 20 wt. %, based on theweight of resin in the final composition.

The polycarbonate used in this composition is derived from bisphenol Aand phosgene. In an alternative embodiment, the polycarbonate resin is ablend of two or more polycarbonate resins.

The aromatic polycarbonate may be prepared in the melt, in solution, orby interfacial polymerization techniques well known in the art. Forexample, the aromatic polycarbonates can be made by reacting bisphenol-Awith phosgene, dibutyl carbonate or diphenyl carbonate. Such aromaticpolycarbonates are also commercially available. In one embodiment, thearomatic polycarbonate resins are commercially available from GeneralElectric Company, e.g., LEXAN™ bisphenol A-type polycarbonate resins.One aromatic polycarbonate is a homopolymer, e.g., a homopolymer derivedfrom 2,2-bis(4-hydroxyphenyl)propane (bisphenol-A) and phosgene,commercially available under the trade designation LEXAN Registered TMfrom General Electric Company.

Branched polycarbonates are prepared by adding a branching agent duringpolymerization. These branching agents are well known and may comprisepolyfunctional organic compounds containing at least three functionalgroups, which may be hydroxyl, carboxyl, carboxylic anhydride,haloformyl and mixtures thereof. Specific examples include trimelliticacid, trimellitic anhydride, trimellitic trichloride, tris-p-hydroxyphenyl ethane, isatin-bis-phenol, tris-phenol TC(1,3,5-tris((p-hydroxyphenyl)-isopropyl)benzene), tris-phenol PA(4(4(1,1-bis(p-hydroxyphenyl)-ethyl)alpha, alpha-dimethylbenzyl)phenol), 4-chloroformyl phthalic anhydride, trimesic acid andbenzophenone tetracarboxylic acid. The branching agent may be added at alevel of about 0.05-2.0 weight percent. Branching agents and proceduresfor making branched polycarbonates are described in U.S. Letters Pat.Nos. 3,635,895; 4,001,184; and 4,204,047.

The preferred polycarbonates are preferably high molecular weightaromatic carbonate polymers have an intrinsic viscosity (as measured inmethylene chloride at 25° C.) ranging from about 0.30 to about 1.00deciliters per gram. Polycarbonates may be branched or unbranched andgenerally will have a weight average molecular weight of from about10,000 to about 200,000, preferably from about 20,000 to about 100,000as measured by gel permeation chromatography. It is contemplated thatthe polycarbonate may have various known end groups.

The level of polycarbonate employed in the composition of the presentinvention ranges from 5 to 90% of the total weight of the composition,more preferably, from 20 to 70% of the total weight of the composition.

Other thermoplastic polymers such as polyamides, polyolefins,polyphenylene ether, polyphenylene sulfide, polyetherimides,organosiloxane rubber, ethylene propylene diene monomer rubber,styrene-butadiene-styrene rubber, styrene-ethylene-butadiene-styrenerubber, acrylonitrile-butadiene-styrene rubber,methacrylate-butadiene-styrene rubber, styrene acrylonitrile copolymer,glycidyl esters, or other polycarbonates can be present in thecomposition in place of polycarbonate, as property modifying polymers.

The polyester composition of the invention may be formed by techniquesknown in the art. The ingredients are typically in powder or granularform, and extruded as a blend, and/or comminuting into pellets or othersuitable shapes. The ingredients may be combined in any manner, e.g., bydry mixing or by mixing in the melted state in an extruder, or in othermixers. For example, one embodiment comprises melt blending theingredients in powder or granular form, extruding the blend andcomminuting into pellets or other suitable shapes. Also included is drymixing the ingredients, followed by mixing in the melted state in anextruder.

The blends of the invention may be formed into shaped articles by avariety of common processes for shaping molten polymers such asinjection molding, compression molding, extrusion, blow molding and gasassist injection molding. Examples of such articles include electricalconnectors, enclosures for electrical equipment, automotive engineparts, lighting sockets and reflectors, electric motor parts, powerdistribution equipment, communication equipment and the like includingdevices that have molded in snap fit connectors. The modified polyesterresins can also be made into films and sheets.

EXAMPLES

The following examples illustrate the present invention, but are notmeant to be limitations to the scope thereof. Examples of the inventionare designated by En and comparative examples are shown by Cn where nstands for the number of the example. The examples were all prepared andtested in a similar manner.

The ingredients of the examples were tumble blended and then extruded ona on a Twin Screw Extruder with a vacuum vented mixing screw, at abarrel and die head temperature between 240 and 265° C. The screw speedwas at 300 rpm. The extrudate was cooled through a water bath prior topelletizing. Test parts were injection molded on an Engel 110T moldingmachine or a van Dorn molding machine with a set temperature ofapproximately 240 to 265° C. The pellets were dried for 2-4 hours at120° C. in a forced air-circulating oven prior to injection molding.

Flow measurement: In this work, three measurement methods tocharacterize flow were used. The flow of different examples wascharacterized normally by one or more of these methods given in thefollowing paragraphs.

Melt Volume Rate (MVR) on pellets (dried for 2 hours at 120° C. prior tomeasurement) was measured according to ISO 1133 method at dwelling timeof 240 seconds and 0.0825 inch (2.1 mm) orifice.

Spiral flow was measured in injection molding machine with a spiralmold. The flow length (in cm) in the mold was measured under the giventest conditions. Melt Temperature, mold temperature, gauge of spiralflow, and boost pressure were 260° C., 66° C., 1.5 mm, and 10 Mpa,respectively. The first 10-15 parts were thrown away until constant flowlength has been reached. The reported values were average of 5 parts.

Capillary viscosity, which is another indicator of melt-flow, wasmeasured by ASTM D3835 or ISO D11433. Dried pellets were extrudedthrough a capillary Rheometer and the force at varied shear rates wasdetermined to estimate the shear viscosity.

Tensile properties were tested according to ISO 527 on 150×10×4×mm(length x wide x thickness) injection molded bars at 23° C. with acrosshead speed of 5 mm/min. Izod unnotched impact was measured at 23°C. with a pendulum of 5.5 Joule on 80×10×4 mm (length x wide xthickness) impact bars according to ISO 180 method. Flexural propertiesor three point bending were measured at 23° C. on 80×10×4 mm (length xwide x thickness) impact bars with a crosshead speed of 2 mm/minaccording to ISO 178.

In other cases, injection molded parts were tested by ASTM. Notched Izodtesting as done on 3×½×⅛ inch bars using ASTM method D256. Tensileelongation at break was tested on 7×⅛ in. injection molded bars at roomtemperature with a crosshead speed of 2 in./min for glass filled samplesand 0.2 in/min for un-filled samples by using ASTM D648. Flexuralproperties were measured using ASTM 790 or ISO 178 method. Biaxialimpact testing, sometimes referred to as instrumented impact testing,was done as per ASTM D3763 using a 4×⅛ inch molded discs. The totalenergy absorbed by the sample is reported as ft-lbs or J.

Oven aging was done by placing molded parts in an air circulating ovenat 155° C. Parts were removed from the oven, allowed to cool andequilibrate at 50% relative humidity for at least two days beforetesting. Oven aging was done as per ASTM D3045.

Flame retardancy tests were performed following the procedure ofUnderwriter's Laboratory Bulletin 94 entitled “Tests for Flammability ofPlastic Materials, UL94.” According to this procedure, materials may beclassified as HB, V0, V1, V2, VA and/or VB on the basis of the testresults obtained for five samples. To achieve a rating of V0, in asample placed so that its long axis is 180 degrees to the flame, theaverage period of flaming and/or smoldering after removing the ignitingflame does not exceed five seconds and none of the vertically placedsamples produces drips of burning particles that ignite absorbentcotton. Five bar flame out time (FOT) is the sum of the flame out timefor five bars, each lit twice for a maximum flame out time of 50seconds. To achieve a rating of V1, in a sample placed so that its longaxis is 180 degrees to the flame, the average period of flaming and/orsmoldering after removing the igniting flame does not exceed twenty-fiveseconds and none of the vertically placed samples produces drips ofburning particles that ignite absorbent cotton. Five bar flame out timeis the sum of the flame out time for five bars, each lit twice for amaximum flame out time of 250 seconds. Compositions of this inventionare expected to achieve a UL94 rating of V1 and/or V0 at a thickness ofpreferably 1.5 mm or lower.

In the following tables, the comparative examples are designated by Cfollowed by a number and the examples of the invention are designated byE followed by a number.

The components used in the examples are given in Table 1. TABLE 1 TestMaterials Abbreviation Material PBT195 Poly(1,4-butylene terephthalate)from General Electric Company intrinsic viscosity of 0.7 cm3/g asmeasured in a 60:40 phenol/tetrachloroethane mixture. PBT315Poly(1,4-butylene terephthalate) from General Electric Company intrinsicviscosity of 1.2 cm3/g as measured in a 60:40 phenol/tetrachloroethanemixture. PC100 PC bisphenol polycarbonate Lexan ® resin from GeneralElectric Company. Mn by GPC against polystyrene standards is 29 Kg/mol.Pentaerythritol Tetrakis(hydroxymethyl)methane;2,2-Bis-(hydroxymethyl)-1,3-propanediol THAM Trishydroxymethylaminomethane as purchased from Aldrich Chemical Company, USA. AO1010Hindered Phenol, Pentaerythritoltetrakis(3,5-di-tert-butyl-4-hydroxyhydrocinnamate) sold as IRAGANOX1010 from Ciba Geigy Glass fiber E glass with diameter of 10 or 13 um.Sizing-coated glass fibers are commercially available from Owens ComingFiberglass as, for example, OCF K filament glass fiber 183F. PEP-QTetrakis(2,4-di-tert-butylphenyl)4,4′-biphenylene diphosphoniteSANDOSTAB PEPQ from Clariant Chemicals. PETS pentaerythritoltetrastearate S2001 Core-shell type impact modifier withsilicone-acrylic-based rubber, METABLEN S-2001 from Mitsubishi Rayon.ABS Acrylonitrile-Butadiene-Styrene copolymer impact modifier, Sold asVHRG or HRG SG24 or HRG360 from General Electric MBSMethacrylate-Butadiene-Styrene emulsion copolymer impact modifier withcore-shell structure, sold as EXL2691 or EXL2650A from Rohm & Haas.Acrylic impact Acrylic impact modifier from Robin and Haas EXL3330modifier Emulsion copolymer of methacrylate-butyl acrylate withcore-shell structure. EPON1001F

from Hexion Specialty Chemical, with an epoxy equivalent molecularweight of 525 to 550. Sodium stearate Catalyst Lotader AX8900Polyethylene/poly(methyl acrylate) copolymer comprising 67 wt% ethylene,25 wt% methyl acrylate, and 8 wt% reactive glycidyl methacrylate groups,sold by Arkema Inc. Hytrel 4056 Poly(butyleneterephthalate)/poly(tetrahydrofuran) copolymer comprising 48 wt%poly(tetrahydrofuran) AO168 2,4-di-tert-butylphenol phosphite, sold asIRGAPHOS 168 from Ciba Geigy

TABLE 2 Unit C1 C2 E1 E2 E3 E4 E5 Component PBT315 % 100 99.5 99.9 99.899.7 99.5 99.0 THAM % 0.0 0.0 0.1 0.2 0.3 0.5 1.0 Pentaerythritol % 0.00.5 — — — — — Properties Spiral flow cm 27 42 29 33 38 55 90 Melt volumerate (MVR) cc/10 min 5.6 17.5 7.5 9.9 11.5 37.0 67.0 at 265° C./2.16Kg/240 s Tensile Modulus GPa 2.6 2.75 2.6 2.58 2.65 2.83 2.88 Elongation% % 51 21 36.1 33.4 31.2 14.7 3.2 Izod Unnotched at 23° C. kJ/m2 210 170186 180 176 128 43

As seen in Table 2 (examples E1 to E5), the variation of the levels ofTHAM has a profound effect on the melt volume rate or spiral flow, bothbeing independent measures of melt flowability of polymer composition.When the amount of THAM is greater than about 1% by weight of polyestercomposition, mechanical properties, particularly impact property (IzodUnnotched) gets affected unacceptably.

As seen in Table 3, in a glass filled polyester formulation (exampleE6), THAM is more efficient in bringing about melt viscosity reductionor improvement in flow than pentaerythritol. THAM is effective inincreasing the MVR as seen for example E7 relative to example C7, bothcontaining ABS as the impact modifier. THAM is more efficient thanpentaerythritol in enhancing the flow with satisfactory retention inmechanical properties. TABLE 3 Unit C5 C6 E6 C7 C8 E7 Component PBT-315% 75 74.75 74.75 65 64.75 64.75 Glass % 25 25 25 25 25 25Pentaerythritol % 0.25 0.25 THAM % 0.25 0.25 ABS HRG360 % 10 10 10 AO1010 % 0.8 0.8 0.8 0.8 0.8 0.8 Properties Melt volume rate (MVR) cc/10min 5.2 12.7 18 2.2 6.1 7.9 at 265° C./2.16 Kg/240 s Spiral flow cm 5377 91 49 75 89 Tensile Modulus GPa 5.91 6.19 6.3 6.19 5.71 5.71 TensileStrength GPa 94 94 94.4 82 79 79 Elongation % % 5.4 4.4 4.3 4.9 4.3 4.3Flexural Modulus GPa 5.52 5.81 5.85 5.34 5.15 5.27 Flexural Strength GPa149.8 150.7 153 128.7 125.5 126.5 HDT ° C. 148 157 165 154 150 155 IzodUnnotched (kJ/m2), 23° C. kJ/m2 49 34 28 45 40 40

In Table 4, flow improvement due to the addition of THAM to apolycarbonate-polyester composition (Example E8) with retention ofmechanical properties is demonstrated. For those skilled in the art, theuse of THAM and other polyhydric additives of this invention for flowpromotion will be possible in analogous types of polycarbonate-polyesteror copolyester blends including transparent compositions. TABLE 4Component Unit C9 E8 PC100 % 75 74.75 PBT-315 % 25 25 THAM % 0.25Properties Melt volume rate (MVR) at 265° C./ cc/10 min. 6 28 2.16Kg/240 s Spiral Flow Cm 34 63 Tensile Modulus GPa 2.41 2.61 Elongation %79 75 Izod Unnotched 23° C. kJ/m2 250 255

TABLE 5 Unit C10 C11 C12 E9 E10 Component PBT-195 % 69.7 59.7 59.2 59.259.2 Pentaerythritol % 0.5 0.5 0.5 Acrylic Impact modifier; Paraloid %10 10 EXL 3300 MBS Paraloid EXL2650A % 10 Metablen S2001 silicone impact% modifier ABS HRG SG24 % 10 Glass; Standard Crystalline glass % 30 3030 30 30 Additives % 0.3 0.3 0.3 0.3 0.3 Properties Melt volume rate(MVR) cc/10 min. 30 7 21 31 32.5 at 265° C./2.16 Kg/240 s CapillaryShear viscosity at Pa-s 84 91 46 42 53 280° C. (1500/s) Izod Unnotched(kJ/m2) kJ/m2 40 54 42 46 44 Heat aged Izod Unnotched kJ/m2 30 50 22 4722 (155° C. 1 week) Tensile Strength (Mpa) Mpa 146 121 116 120 116 Heataged Tensile Strength Mpa 157 133 119 118 110 (155° C. 1 week) TensileModulus (Mpa) Mpa 9350 8580 8600 8590 8750 Flexural Strength (Mpa) Mpa217 191 172 182 175 Flexural Modulus (Mpa) Mpa 8450 7700 7700 7800 7900

As seen in Table 5, a flow-enhancing agent such as pentaerythritol ishighly effective in increasing the flow of a composition comprisingacrylic modifier or MBS (Example E9 and E10). Acrylic impact modifier isthe most effective among the impact modifiers studied, in bringing aboutsimultaneous improvements in flow and heat ageing stability.Compositions containing either MBS (example, E10) or acrylic impactmodifier (example, E9) are superior to comparative example C12 inobtaining superior balance of flow and heat-ageing stability. TABLE 6Unit C13 E11 E12 C14 E13 E14 Component PBT 195 % 49.2 48.7 48.7 49.348.8 48.8 Pentaerythritol % 0.5 0.5 0.5 0.5 Acrylic Impact modifier;Paraloid % 5 5 5 5 EXL 3300 MBS — — 5 — — 5 Brominated PC Oligomer, 52%Br % 10 10 10 Brominated Acrylate % 10.5 10.5 10.5Poly(pentabromobenzylacrylate) Sb₂O₃ Masterbatch; % 4 4 4 4.2 4.2 4.280% in PBT 195 Encapsulated PTFE % 0.9 0.9 0.9 0.7 0.7 0.7 ZincPhosphate % 0.6 0.6 0.6 Glass % 30 30 30 30 30 30 Additives % 0.3 0.30.3 0.3 0.3 0.3 Properties Melt Volume Rate (250° C., cc/min 4 12 8 6 159 2.16 Kg, 240 s) Izod Unnotched kJ/m2 39 34 26 42 38 32 Izod Unnotchedon heat-aging at kJ/m2 29 26 23 34 26 25 155° C. for 1 week IzodUnnotched on heat-aging at kJ/m² 34 35 25 37 28 21 155° C. for 2 weeksTensile Strength (Mpa) Mpa 122 116 114 124 122 118 Tensile Modulus (Mpa)Mpa 10165 10415 10489 10350 10355 10307 Tensile Elongation % 2.2 1.6 1.61.8 2.1 2.0 Flexural Strength (Mpa) Mpa 185 176 170 188 178 170 FlexuralModulus (Mpa) Mpa 8450 8500 8700 8900 8600 8600 UL Flame rating 1.5 mmV0 V0 V0 V0 V0 V0

As seen in Table 6, a flame retardant PBT composition containingpentaerythritol as the flow-enhancing ingredient shows superior flowproperties. Also, a composition containing pentaerythritol and anacrylic impact modifier (Examples E11 or E13) provides a superiorcombination of flow improvement and heat-ageing stability propertiesthan that containing MBS as the impact modifier (examples E12 or E14).Acrylic impact modifier-based compositions provide not only improvedflow properties but also good impact resistance and heat-ageingresistance characteristics. The use of pentaerythritol as the flowenhancing additive does not affect the flame retardant rating for themolded bars of 1.5 mm thickness, as seen for comparative examples C13and C14 as well as the inventive examples E11, E12, E13 and E14. TABLE 7Unit C15 C16 E15 E16 Component PBT 195 % 27.1 24.6 26.975 24.475 PBT315% 27.1 24.6 26.975 24.475 THAM % 0.25 0.25 Acrylic Impact modifier; % 55 Paraloid EXL 3300 Brominated PC oligomer % 10 10 10 10 52% Br Sb₂O₃Masterbatch; % 4 4 4 4 80% in PBT 195 Encapsulated PTFE % 0.9 0.9 0.90.9 Zinc Phosphate % 0.6 0.6 0.6 0.6 Glass % 30 30 30 30 PETS % 0.2 0.20.2 0.2 AO1010 % 0.1 0.1 0.1 0.1 Properties Spiral Flow cm 52 42.5 6463.5 Capillary Shear pa-s 233 231 151 143 viscosity at 250° C. (1500/s)Izod Unnotched (Initial) kJ/m2 49.08 51.20 37.88 44.79 Izod Unnotched(After kJ/m2 36.08 42.50 18.63 27.13 Heat aging at 155° C. for 1 week)UL-94 (1.5 mm) V0 V0 V0 V0

Table 7 illustrates that THAM which contains one primary amino group canbe used as a flow enhancing additive in flame retardant polyesterformulations as well.

Comparative Examples 17-21 and Example 17 (Table 8) illustrate theimprovement in both melt flow and hydrolytic resistance of polyestercompositions comprising an aromatic epoxy compound and an aminoalcohol.All component amounts are reported in weight percent. For theseexamples, the components were processed as above, except that the screwspeed of the extruder was 100 rpm, and test articles were molded on avan Dom molding machine with a set temperature of approximately 250° C.,and the pellets were dried for 3-4 hours at 120° C. in a forcedair-circulating oven prior to injection molding.

Flow properties were measured as described above. Tensile propertieswere tested on Type I tensile bars at room temperature with a crossheadspeed of 2 in./min. according to ASTM D638.

Notched Izod testing was performed on 3×½×⅛ inch (76×13×3 mm) barsaccording to ASTM D256 at 23° C.

Unnotched Izod testing was done on 3×½×⅛ inch (76×13×3 mm) barsaccording to ASTM D4812 at 23° C.

The flexural bars were tested for flexural properties as per ASTM 790.

The retention of tensile stress at yield was calculated by dividing thetensile stress after heat aging at 90° C. and 95% relative humidity forthe indicated number of days, by the tensile stress of the test sampleprior to heat aging, and then multiplying by 100. TABLE 8 C17 E17 C18E18 Component PBT195 61.25 61.50 66.25 66.50 Acrylic impact modifier5.00 5.00 0 0 Glass fiber 30.00 30.00 30.00 30.00 EPON1001F 3.00 3.003.00 3.00 THAM 0 0.25 0 0.25 Pentaerythritol 0.50 0 0.50 0 PETS 0.200.20 0.20 0.20 AO1010 0.05 0.05 0.05 0.05 Sodium stearate 0.05 0.05 0.050 Properties Capillary viscosity 200.9 674.4 129.1 373.0 at 24/s (Pa-s)Capillary viscosity 97.5 170.6 80.1 128.0 at 664/s (Pa-s) Capillaryviscosity 69.8 118.9 62.7 102.0 at 1520/s (Pa-s) Capillary viscosity66.4 97.2 59.1 83.0 at 2286/s (Pa-s) Capillary viscosity 44.3 65.0 41.654.0 at 5886/s (Pa-s) Tensile modulus (MPa) 10900 11300 11300 12300Tensile stress at yield 107.0 110.0 98.8 107.0 (MPa) Tensile stress atbreak 107.0 110.0 98.8 107.0 (MPa) Tensile elongation at 1.7 1.7 1.5 2.0yield (%) Tensile elongation at 1.7 1.7 1.5 2.0 break (%) Flexuralmodulus (MPa) 8250 8190 8190 8760 Notched Izod (J/m) 175.0 175.0 171.0175.0 Unnotched Izod (J/m) 87.2 90.2 85.7 90.0 Retention of tensilestress (%) After 7 days 79 97 60 89 After 14 days 61 87 54 70 After 21days 57 71 — —

It can be seen from Table 8 that a balance of good flow properties andretention of tensile stress are obtained only when the compositionscomprise a combination of the aromatic epoxy and the aminoalcohol.Comparative examples 17 and 18 comprise pentaerythritol as thepolyhydric alcohol, while examples 17 and 18 comprise an aminoalcohol,tris(hydroxymethyl)aminomethane. All four examples show excellent flowproperties, as demonstrated by the capillary viscosity. However,Comparative examples 17 and 18 have poorer retention of tensile stressafter heat aging at 90° C. and 95% relative humidity when compared toexamples 17 and 18. Example 17 shows a 71% retention after 21 days,compared to only 57% for comparative example 17, while example 18 showsa 70% retention after 14 days, compared to only 54% for comparativeexample 18.

While the invention has been illustrated and described in typicalembodiments, it is not intended to be limited to the details shown,since various modifications and substitutions are possible withoutdeparting from the spirit of the present invention. As such,modifications and equivalents of the invention herein disclosed mayoccur to persons skilled in the art using no more than routineexperimentation, and all such modifications and equivalents within thespirit and scope of the invention as defined by the following claims.

1. A composition comprising, a polyester; 0.05 to 2 weight percent,based on the total weight of the polyester, of an aminoalcohol of theformula (III)

wherein R₃ is a C1-C20 alkyl group optionally having one or more hydroxygroup substituents, a C3-C20 cycloalkyl group, a C6-C20 aryl group, aC1-C20 alkoxy group optionally having one or more hydroxy groupsubstituents, or a C6-C20 aryloxy group; and an aromatic epoxy compound,in an amount sufficient to provide 5 to 300 milliequivalents of epoxyper kilogram of polyester.
 2. The composition of claim 1, having aspiral flow value that is 30% or more of the spiral flow value of thesame composition without the aminoalcohol and aromatic epoxy compound,wherein each spiral flow is measured at a melt temperature of 250-260°C., a mold temperature of 66° C., a gauge of 1.5 mm, and a pressure of10 MPa.
 3. The composition of claim 1, having capillary viscosity thatis 30% or less of the capillary viscosity of the same compositionwithout the aminoalcohol and the aromatic epoxy compound, wherein eachcapillary viscosity is measured in accordance with ASTM D3865.
 4. Thecomposition of claim 1, wherein the tensile stress at yield of anarticle comprising the composition retains 85% or more of its initialtensile strength after aging at 90° C. for 168 hours at 95% humidity,wherein each tensile strength is measured in accordance with ASTM D638.5. The composition of claim 1, wherein an article comprising thecomposition retains more of its tensile strength after aging at 90° C.for 168 hours at 95% humidity, relative to the same composition withoutthe aromatic epoxy compound, wherein tensile strength is measured inaccordance with ASTM D638.
 6. The composition of claim 1, wherein thepolyester comprises units of the formula (II)

wherein R′ is a C2-C20 dehydroxylated residue derived from an aryl,alkane, or cycloaliphatic diol or a chemical equivalent thereof, and Ris a C6-C30 decarboxylated residue derived from an aryl, aliphatic, orcycloaliphatic diacid.
 7. The composition of claim 1, wherein thepolyester further comprises amide units.
 8. The composition of claim 1,wherein the polyester comprises a poly(alkylene phthalate), apoly(alkylene isophthalate), a poly(alkylene terephthalate), apoly(cycloalkylene terephthalate), a poly(cycloalkylene cycloaliphaticdicarboxylate), a poly(alkylene dicarboxylate), or a combinationcomprising at least one of the foregoing polyesters.
 9. The compositionof claim 1, wherein R′ is derived from an alkanediol and/or acycloaliphatic diol or chemical equivalent thereof, and R is derivedfrom an aromatic diacid, an aliphatic diacid, and/or a cycloaliphaticdiacid or chemical equivalent thereof.
 10. The composition of claim 1,wherein R is derived from a mixture of terephthalic acid and isophthalicacid or chemical equivalent thereof, and R′ is derived from a C2-C4alkanediol or chemical equivalent thereof.
 11. The composition of claim1, wherein R₃ is —CH₃, —CH₂CH₃, or —CH₂OH.
 12. The composition of claim1, wherein the aromatic epoxy compound has an epoxy equivalent weight of100 to 3,000.
 13. The composition of claim 1, wherein the aromatic epoxycompound is of the formula (IV)

wherein R^(a′) and R^(b′) are each independently halogen or C1-C12alkyl, X^(a) is a substituted or unsubstituted C1-C18 alkylidenebridging group or a substituted or unsubstituted C3-C18 cycloalkylidenebridging group, n is 1 to 6, and r and s are each independently 0 to 4.14. The composition of claim 1, further comprising a catalyst, whereinthe catalyst is a hydroxide, hydride, amide, carbonate, borate,phosphate, C2-C18 enolate, C2-C36 dicarboxylate, or C2-C36 carboxylateof a metal; a Lewis acid catalyst; a C1-C36 tetraalkyl ammoniumhydroxide or acetate; a C1-C36 tetraalkyl phosphonium hydroxide oracetate; an alkali or alkaline earth metal salt of a negatively chargedpolymer; or a combination comprising at least one of the foregoingcatalysts.
 15. The composition of claim 14, wherein the catalyst issodium stearate, sodium carbonate, sodium acetate, sodium bicarbonate,sodium benzoate, sodium caproate, potassium oleate, a boron compound, ora mixture comprising at least one of the foregoing salts.
 16. Thecomposition of claim 1, wherein the polyester has a molecular weight of10,000 to 120,000 Daltons.
 17. The composition of claim 1, furthercomprising an anti-oxidant, a filler, a colorant, a mold release agent,a nucleating agent, a UV light stabilizer, a heat stabilizer, alubricant, or a combination comprising at least one of the foregoingadditives.
 18. The composition of claim 17, further comprising 5 to 50weight percent of reinforcing filler, based on the total weight of thecomposition.
 19. The composition of claim 18, wherein reinforcing fillercomprises carbon fibers, short glass fibers, long glass fibers, mica,talc, wollastonite, clay, fibrillated tetrafluoroethylene, polyesterfibers, aramid fibers, or a combination comprising at least one of theforegoing fillers.
 20. The composition of claim 1, further comprising0.1 to 25 weight percent of an acrylic impact modifier, based on thetotal weight of the composition.
 21. The composition of claim 19,wherein the acrylic impact modifier comprises a multi-phase compositeinterpolymer comprising about 25 to 95 weight percent of a first acrylicelectrometric phase polymerized from a monomer system comprising about75 to 99.8% by weight C1-C14 alkyl acrylate, 0.1 to 5% by weightcrosslinking member, 0.1 to 5% by weight graftlinking monomer, saidcrosslinking monomer being a polyethylenically unsaturated monomerhaving a plurality of addition polymerizable reactive groups and about75 to 5 weight percent of a final, rigid thermoplastic acrylic ormethacrylic phase polymerized in the presence of said elastomer.
 22. Thecomposition of claim 1 further comprising a polycarbonate, polyamide,polyolefin, polyphenylene ether, polyphenylene sulfide, polyetherimide,organosiloxane rubber, ethylene propylene diene monomer rubber,styrene-butadiene-styrene rubber, styrene-ethylene-butadiene-styrenerubber, acrylonitrile-butadiene-styrene rubber,methacrylate-butadiene-styrene rubber, styrene acrylonitrile copolymeror glycidyl ester impact modifier.
 23. The composition of claim 1,wherein the composition further comprises a flame retarding component.24. An article comprising the composition of claim
 1. 25. The article ofclaim 24, wherein the article is an extruded or injection moldedarticle.
 26. The article of claim 25, in the form of a component of anelectronic device.
 27. A method of forming an article, comprisingshaping, extruding, blow molding, or injection molding the compositionof claim 1 to form the article.
 28. A method of forming a composition,comprising blending the components of the composition of claim
 1. 29. Acomposition comprising a polyester comprising units of the formula (II)

wherein R′ is derived from a mixture of terephthalic acid andisophthalic acid or a chemical equivalent thereof, and R′ is derivedfrom a C2-C4 alkanediol or a chemical equivalent thereof; 0.01 to 1weight percent, based on the total weight of the polyester, of anaminoalcohol of the formula(III)

wherein R₃ is —CH₃, —CH₂CH₃, or —CH₂OH; an aromatic epoxy compound ofthe formula (IV)

wherein X^(a) is a substituted or unsubstituted C1-C3 alkylidenebridging group, n is 1 to 6, and r and s are each 0, in an amountsufficient to provide 5 to 150 milliequivalents of epoxy per kilogram ofpolyester; and a catalytically effective amount of an alkali metal saltof a C8-C36 carboxylic acid; wherein the composition has a spiral flowvalue that is 30% or more of the spiral flow value of the samecomposition without the aminoalcohol and aromatic epoxy compound,wherein each spiral flow is measured at a melt temperature of 250-260°C., a mold temperature of 66° C., a gauge of 1.5 mm, and a pressure of10 MPa; and the tensile stress at yield of an article comprising thecomposition retains 85% or more of its initial tensile strength afteraging at 90° C. for 168 hours at 95% humidity, wherein each tensilestrength is measured in accordance with ASTM D638.
 30. A compositioncomprising a polyester comprising units of the formula (II)

wherein R′ is derived from a mixture of terephthalic acid andisophthalic acid or a chemical equivalent thereof, and R′ is derivedfrom a C2-C4 alkanediol or a chemical equivalent thereof; 0.01 to 1weight percent, based on the total weight of the polyester, of anaminoalcohol of the formula(III)

wherein R₃ is —CH₃, —CH₂CH₃, or —CH₂OH; an aromatic epoxy compound ofthe formula (IV)

wherein X^(a) is a substituted or unsubstituted C1-C3 alkylidenebridging group, n is 1 to 6, and r and s are each 0, in an amountsufficient to provide 5 to 150 milliequivalents of epoxy per kilogram ofpolyester; and a catalytically effective amount of an alkali metal saltof a C8-C36 carboxylic acid; wherein the composition has a spiral flowvalue that is 30% or more of the spiral flow value of the samecomposition without the aminoalcohol and aromatic epoxy compound,wherein each spiral flow is measured at a melt temperature of 250-260°C., a mold temperature of 66° C., a gauge of 1.5 mm, and a pressure of10 MPa; and an article comprising the composition retains more of itstensile strength after aging at 90° C. for 168 hours at 95% relativehumidity, relative to the same composition without the aromatic epoxycompound, wherein each tensile strength is measured in accordance withASTM D638.